Let me start by saying, don't use good nugs for butter unless you've got some medical reason to prevent you from smoking. My .02. The only reason I even made it was to not waste all of the clippings that had PLENTY of tricombs on them. To do it again, I would make hash.
I had the biggest crockpot wally world had. I cook. I didn't get it for this. I took all of my trimmings and stems and had to cram them in there. I filled it with water and added 2lbs of butter. I set it on low and let it go for 36 hours(8 prolly would have sufficed). I checked it and kept topping it off with water. BTW. Do this in the garage, if you can. That's where I did it. Stinks like a bitch! When I was done cooking it, I starting pulling the plant material out of the water but wrung the water out of the handfuls back into the pot. Once most of it was out, I strained the water as I filled butter or tupperware bowls with it. Put all of this in the fridge or one in the freezer if you need some quick. Once the green butter rises and hardens, just pull it off of the water and put in a new bowl. Heat in microwave if you want it to not look like a bunch of pieces in the bowl. I used this stuff in anything that called for butter(brownies, cake, choco-chip cookies, etc). I used 50-100% more than the recipe called for(you'll get a feel for what stuff can handle more butter). I gave some brownies to some seasoned vets to see the phantom menace when it came out. They could barely stand. I ate two the night b4 that and almost threw up. I had a halloween party and made choc-chips. Nobody was eating them. My friend guilted me into putting a warning sign next to them(I never told anyone they were laced). I wrote "pot cookies". They disappeared in like 2 minutes. Anyways, that's my experience.